Insulator structure



Aug. 20; 1929. w NAYLOR 1,725,097

INSULATOR STRUCTURE Filed June 16, 1927 ATTORNEY Patented Aug. 20, 1929.

UNITED STATES PATENT OFFICE.

HOUSE E-LEGTR-IC & MANUFACTURING VANIA.

INSULATOR Application filed June 16,

My invention relates to insulators and particularly to insulators and adjacent metal parts thereof that are subjected to relatively high voltages.

In insulators for operation in connection with high voltages, such as transmis ionline insulators, every precaution as to con struction, mounting and operation necessary by reason of the importance of maintaining service and the dangers and lo sometimes attending the breakdown of the. insulators.

F lashover is a common type of insula failure that is caused by lightning V and other phenomena which are not all. thoroughly understood, among which is the failure of the insulator by flashovcr during bright sunlight conditions.

It is thought that electron emission from the metal parts in the strong electrostatic insulator field, whether that emission be caused by sunlight or by the field as charged from the line, may cause a critical condition at, or near which, many flashovers which ordinarily occur, other than those caused by strong surges, might readily be prevented.

In any event, it is one of my objects to improve the operation of high-voltage insulators by increasing the flashover-voltage values thereof.

Another object of my invention is to protect a metal member of an insulator against weather effects in a manner different from usual practice.

Another object of my invention is to provide an insulator that shall be simple and durable in construction, economical to manufacture and effective in its operation.

With such objects in View, as well as other advantages which may be incident to the utilization of the improvement, the invention consists in the parts and combinations thereof hereinafter set forth and claimed, with the understanding that the several nec essary elements constituting the same may be varied in proportion, arrangement and. texture without departing from the nature and scope of the invention.

Figure 1, of the accompanying drawings, is a perspective view of a portion of a transmissionline main support, an insulator and a conductor embodying my invention, and

Fig. 2 is an enlarged view, partially in COIJIPANY, A CORPORATION OF PENN$YL- STRUCTURE.

1927. Serial N0. 199,173.

section and partially in side elevation, of an insulator unit shown in Fig. 1.

As shown in Fig. 1, the device comprises, in general, a main supporting element 2, an insulator secured to the element 2, as by a bolt 4, and a clamp 6 secured to the lower end 3, by a bolt 7, and supporting a con ductor 8. The conductor 8 is secured in a position in the clamp 6 as by a U-bolt and nut device 9.

The element 2 is a metal bar of substantially T-shape in cross-section and may constitute a portion of a transmission-tower or pole, cross arm, or other main supporting structure. 7

The insulator 3 is of a usual suspension type comprisin a plurality of flexibly con nected units 10 that are similar to each other. Fig. 2 shows an enlarged view of one of these units.

Referring to Fig. 2, the unit 10 comprises an insulating or dielectric member having a recessed head portion 12, a lower main petticoat portion 14: and undersurface corrugations 15. A metal cap 16 is secured in position over the head portion 12, as by a body of cement 17 and is provided with a clevis portion 18, in a usual and well known manner.

A metal pin has a shank portion 20 and an enlarged head portion 21 secured in the head portion 12, as by a body of cement 22, and a normally exposed outer end or eyeportion 23.

In all of the above mentioned and described structure, the parts are of usual and well known construction.

In accordance with my invention, all of the metal parts of the structure, within a certain distance of the strong electrostatic field of the insulator, are coated with insulating material, as indicated by a shaded area 24: on the element 2, coatings 25 on the cap 16, a coating 27 on the clamp 6 and a coating 28 on the conductor 8.

The coatings 24 and 28 on the element 2 and the conductor 8, respectively, extend for certain distances away from the adjacent ends of the insulator 3 and may be of any suitable material, such as asphaltum.

As indicated in Fig. 2, the coating 25 is preferably constructed of vitreous enamel as are also, a coating 30 on the eye or exposed portion of the pin 23 and the coating 27 on the clamp 23. Other suitable coatings, such as moulded hard rubber, synthetic resin compounds and varnished cloth may be employed.

In the above described structure, in which all of the metal parts, including the bolts 4:, 7 and 9, are coated with insulating material, the voltage value at which flashover occurs is increased. I have determined this fact by actual test of a series of the units 10 having the coatings 25 on the caps 12, as shown.

Whether this result is obtained in accordance with the above mentioned theories is immaterial, it being a fact that an insulator soconstructed shows appreciably improved characteristics over a similar insulator having exposed metal surfaces.

Further, since vitreous enamel is hard and durable, the metal parts coated therewith, or with a similar substance, are protected against weather effects substantially as well as though they were galvanized.

/Vhil-e I have shown and described a particular form of my invention, changes may be effected therein without departing from the spirit and scope thereof as set forth in the appended claims.

I claim as my invention:

1. In combination, a main metallic support, an insulator structure supported there- 3. In combination, in a high-voltage sus pension insulator of the cap-and-pin type, a body of inorganic dielectric material having a head portion of inverted substantially cup-shape and an annular surface-creepage petticoat adjacent to its lower open end, a tension terminal pin secured in "position in said head portion, a metal tension terminal cap secured in position over said head portion and a coating of vitreous enamel entirely covering the normally exposed surfaces of said tension terminal cap.

' In testimony whereof, I have hereunto subscribed my name this 7th day of June 1927.

WILLIAM K. NAYLOR. 

